Fuel injection apparatus for internal combustion engines

ABSTRACT

A fuel injection apparatus incorporating a carburettor means for starting wherein the carburettor means comprises a fuel jet element mounted in fuel delivery relation to a carburettor air inlet passageway communicating with a main air inlet duct through the fuel injection apparatus at a position downstream of manually controlled throttle valve means, and air and fuel cut-off valves are provided for cutting off the flow of air and fuel respectively through the carburettor air inlet passageway and the fuel jet element by operation of a plunger in a carburettor bore in the body of the apparatus under pressure of fuel from a high pressure fuel pump feeding fuel injectors when injecting pressure is attained.

ilnite States Patent [191 Pagdin FUEL INJECTION APPARATUS FOR INTERNAL COMBUSTION ENGINES [75] Inventor: Brian Colin Pagdin, Sutton Coldfield, England [73] Assignee: GKN Transmissions Limited,

Birmingham, England [22] Filed: Mar. 5, 1973 [21] Appl. No.: 338,680.

[30] Foreign Application Priority Data 58]; Field of seamin ..f1'l'123/179 L, 32 R, 32 swc [56] I References Cited apparatus under pressure of fuel from a high pressure UNITED STATES PATENTS if: psugztpgiti'eeegmg fuel lIljCCtOXS when in ecting presl,005,l l8 l0/l9ll ,Rabsilber 123/32 SW 2,277,130 3/1942 Miller -123/32 SW 5 Claims, 5 Drawing Figures 21 $1 20a 2 26; u 3 A I 42 :':1:::': l i 'i -+iP- 2,534,346 12/1950 Fenney ..l23/32R Primary Examiner-+Laurence M. Goodridge Assistant ExaminerRonald B. Cox

' )ittorney, Agent, or Firm-Spencer & Kaye [5 7] ABSTRACT A fuel injection apparatus incorporating a carburettor means for starting wherein the carburettor means comprises a fuel jet element mounted in fuel delivery relation to a carburettor air inlet passageway communicating with a main air inlet duct through the fuel injection apparatus at a position downstream of manu-- ally controlled throttle valve means, and air and fuel cut-off valves are provided for cutting off the flow of air and fuel respectively through the carburettor air inlet passageway and the fuel jet element by operation of a plunger in a carburettor bore in' the body of the as I Pmammw 81m 4 3.839.998 SHEEI 1 BF 5 BLOW-OFF VALVE METERING MEANS I 14: 1

-20- VALVE MEANS 19 3O v H|e|-| PRES- 27 -29 16 suns PUMP r CARBURETOR comsusnou DEVICE ENGINE 17 2( 26 26 22 INJECTOR INJECTOR maze-roa- PRESSURE FILTER PUMP PATENTEDBBT 81m SHEET 3 OF 5 FIG. 3.

PATENTED BET 81974 SHEET [If 5 FIG.

PATENTED BET 1974 3,839,998 SHEET SN 5 BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to fuel injection apparatus for an internal combustion engine comprising a body having an air inlet duct, an adjustable throttle valve means controlling the flow'of air through said duct to the em gine, fuel inlet means, and fuel outlet means for connection to one or more injectors, pump means for establishing flow of fuel from said inlet means tosaid outlet means and for establishing injecting pressure for delivery of fuel from said injector or injectors, metering means for delivering a measured quantity of fuel to said outlet means in each cycle of operation of the engine, drive means for driving said metering means in timed relation with the engine, sensing means controlling voperation of the metering means for sensing parameters selected to provide a proper air-to-fuel ratio for a range of engine loads and external conditions of operation, and carburettor means including a carburettor air inlet passageway of smaller cross-sectional area than that of said air inlet duct, and communicating with the latter at a position downstream of said throttle valve means, a fule jet element communicating at its inlet end with said fuel inlet means and having a delivery end mounted in fuel delivery relation with said carburettor air inlet passageway to deliver fuel thereto in response to depression of pressure in said air inlet duct below atmospheric pressure during starting of theengine. The invention has been developedin relation to fuel injection apparatus of the kind specified intended for use in conjunction with an engine having one or more cylinders and having ignition means for igniting the airfuel mixture in the cylinders by means of spark discharge. The fuel is a volatile hydro-carbon such as petrol.

Again, the invention has been developed primarily in relation to a fuel injection apparatus of the kind specitied wherein the metering means comprises a metering cylinder containing a free or shuttle piston element movable between stops, the distance between which is determined by an adjustment means to determined the quantity of fuel delivered each stroke of the free piston, and cylinder spaces on opposite sides of the piston are connected in successive cycles of operation through commutating valve means respectively to the pump means and to the outlet means, the other valve space in each case being connected respectively to the outlet means and the pump means. When the fuel injection apparatus is intended to be utilised in conjunction with a multi-cylinder engine the outlet means would com: prise a plurality of outlets, and the commutating valve means would be associated with, or would be constructed to act as, a distributing valve means to effect delivery of fuel from respective outlets in the proper succession.

2. Description of the Prior Art Previously proposed carburettor means in fuel injection apparatus of the kind specified has involved certain disadvantages. Firstly, the carburettor means was not entirely disabled during subsequent operation of the associated engine, e.g., it remained operative when the engine was running in the cold condition. Consequently during this phase precise control over the airto-fuel ratio'would not be established, thereby leading to a degree of atmospheric pollution not acceptable by present and future standards.

Secondly, the bringing into operation and the eventual disablement of the carburettor means entailed the provision of complex electrical circuitry which not only give rise to high manufacturing cost but also would be a potential source of maintainence problems and unreliability.

One object of the present invention is to providea simple and effective carburettor means in fuel injection apparatus of the kind specified which will disable the carburettor means as soon as the fuel injection apparatus is ina condition to supply fuel to the engine through the injectors, thereby avoiding any phase during which there is lack of precise control over the air-to-fuel ratio.

A further object is so to simplify disablement of the carburettor during the running phase of the engine as to reduce manufacturing cost and increase reliability.

SUMMARY OF THE INVENTION In a fuel injection apparatus of the kind specified we provide the improvement comprising air cut-off valve means movable between open and closed positions for establishing and cutting off air flow through said carburettor air inlet passageway, fuel cut-off valve means movable between open and closed positions to provide for delivery and cut-off of fuel from said delivery end of said fuel jet elements, fluid pressure actuated operating means for said air cut-off valve means and said fuel cut-off valve means and connected by fuel duct means with an outlet of said pump means to close said cut-off valve means in response to the attainment of fuelinjection pressure.

In one simple and advantageous arrangement according to the invention the body of the fuel injection apparatus is formed with a carburettor bore containing said jet element and said air cut-off valve means and said fuel cut-off valve means, both of these cut-off valve means being closed by operation of a'piston element in the bore under pressure of fuel from the outlet of said pump means upon attainment of injecting pressure, the

carburettor air inlet passageway communicating with said carburettor bore at a position adjacent to the delivery end of said fuel element.

I BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described, by way of example, with reference to the accompanying drawings wherein:

FIG. 1 is a schematic diagram illustrating the main components of a fuel supply system incorporating a fuel injection apparatus in accordance with the invention; FIG. 2 is a view inside elevation and partly in crosssection illustrating a constructional embodiment of the fuel injection apparatus in accordance with the invention;

FIG. 3 is a plan view in cross-section on the line 33 of FIG. 2 illustrating the carburettor device incorporated in the fuel injection apparatus;

FIG. 4 is a cross-sectional viewon the line 4-4 of FIG. 2 of the body of the apparatus; 7

FIG. 5 is a diagrammatic view illustrating the general arrangement and manner of operation of the metering means comprising the metering piston and cylinder unit and a commutating and distributing valve means of the fuel injection apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT The complete system for the supply of fuel and the constructional embodiment of apparatus are more fully described in our copending application Ser. No. 338,681 to which reference may be made. For convenience the main features of the fuel supply system and fuel injection apparatus will be referred to before describing in more detail those parts of the embodiment of fuel injection apparatus with which the present invention is concerned.

The fuel supply system shown in FIG. 1 comprises a fuel tank feeding the inelt of a fuel injection apparatus through a filter 12 and low pressure pump 13 by way of pipes 11 and '14, excess fuel being returned to the tank by pipe 32.

The fuel injection apparatus is shown mounted on the inlet manifold 16 of a V-six cylinder internal combustion engine 17 having injectors 26 fed by pipes 27 from outlets of the fuel injection apparatus. The injectors include spring loaded injector valves which are normally closed but open at a predetermined injecting pressure of fuel delivered to the injectors.

The fuel injection apparatus includes main units or asssemblies which are identified by blocks in the schematic circuit diagram and by corresponding references in FIG. 2 as follows.

A high pressure pump 18 of the rotary vane type develops the requisite injecting pressure and supplies fuel such as petrol from an inlet 14a to a metering means through the intermediary of a commutating and distributing valve means 19 which serves to operate a free or shuttle piston 20a of the metering means and also distribute the fuel successively to six outlets connected by pipes such as 27 to the injectors 26.

Excess fuel is returned through blow-off valve 31 to pipe 32.

The stroke of the piston 20a of the metering means 20 between stops 20b, 20c is determined by sensing or control means 29 which includes an evacuated bellows 29a for sensing absolute pressure in a chamber 34 forming part of the air inlet duct to which admission of air is controlled by a throttle valve fitting 35 incorporating a manually operable butterfly valve plate 36.

Temperature of the air in the chamber 34 is sensed by a temperature sensing element 37 of the wax capsule type, while a further temperature parameter, for example engine cooling fluid temperature, is sensed by a temperature sensing element 38. Mechanical outputs in the form of axial displacements of the elements 37 and 38 are added in an addition mechanism 39, the output element of which is a rotary sleeve 40 on which one end plate of the bellows 29a is fixed.

The other end plate of the bellows carries a cam element 41 having a frusto-conical cam surface eccentric to axis 41a so that axial displacement of the cam in consequence of pressure sensing by the bellows 29a and rotation of the cam in consequence of sensing of temperature parameters by elements 36 and 37 are multiplied and applied to tappet 42 serving to adjust the position of the lower stop of the metering piston.

The general arrangement and manner of operation of the metering means 20 and the commutating and distributing valve means 19 is illustrated in FIG. 5.

Rotary valve plates 48 and 49 which are secured together are supported and rotated by carrier 47 and valve plate 48 has the T-shaped cavity formed in its left-hand face, as seen in FIG. 5, with the limb b6 being longer than the other limbs b2 and b4 so as to overlap distributing port d in plate 49. The valve plates have ports each designated by letters b, c and f with a suffix l to 6 pertaining to the particular outlet g1 to g6 and hence cylinder No. l to cylinder No. 6 of the engine.

Full line arrows 43 illustrate the flow of fuel from the high pressure pump 18 in one cycle to the upper cylinder space s1 of the metering cylinder 44, while broken line arrows 4S illustrate the flow of fuel from the lower cylinder space s2 to one of the outlets g6. In this cycle of operation fuel from the high pressure pump traverses ports a1, b1, cl, e1 to reach cylinder space s1. Fuel from cylinder space s2 traverses ports e2, c4, limb b4 of a T-shaped cavity, b6 thereof, port d, f6 and g6.

A supplementary pressure sensing means in the form of an accelerator piston 50 is rotatably mounted on the output sleeve 40 through the intermediary of a substantially sealed bearing 51 and undergoes displacement to the right in response to sudden opening of the throttle valve producing a sudden increase of absolute pressure in the chamber 34. This displaces the bellows and the cam element to the right and lowers the stop 200 to produce a short term enrichment of the mixture. The bearing 51 allows leakage of air from one side of the piston to the other at a slow rate and the piston thus returns to its initial position by virtue of a spring 52 incorporated in the adding mechanism 39.

The pressure of fuel delivered from the high pressure pump 18 may be of the order of 120 lbs. per square inch but this is not developed at cranking speeds which are capable of being attained by operation of a nonnal starter motor on the associated engine.

Accordingly the fuel injection apparatus includes a carburettor device 30 which comes into operation only during starting operations at cranking speeds.

It is necessary to prevent duplicate delivery of fuel by way of both the carburettor device and the injectors of the fuel injection apparatus, and accordingly a controlling signal is applied to the carburettor to disable this in a manner such as to prevent the delivery of fuel from the carburettor device when conditions of operation in the fuel injection apparatus are such that delivery of fuel from the outlets thereof to the injectors is established. One convenient signal which may be employed for this purpose is a fluid pressure signal derived from the output side of the high pressure pump.

The carburettor device is illustrated more particularly in FIG. 3 and FIG. 4 and comprises a carburettor bore formed in the body 33 of the fuel injection apparatus along an axis parallel to that of the driving shaft and the bellows and situated about midway between these components in that wall of the body 33 which forms the boundary between the chamber 34 on the one hand and the chamber in which the metering cylinder block, commutating and distributing valve means, and high pressure pump on the other hand are accommodated.

The carburettor bore 100 includes portions 101 and 102 respectively of larger and smaller diameters. Slidably mounted on the smaller diameter portion 102 is one element 103 of a jet assembly. Such element comprises an inner tube 104 having a fuel passageway 105 extending axially through it and terminating in an end portion 106 of enlarged diameter containing a threshold valve which includes a valve seat elemnet 107, a ball 1% and a biasing coiled compression spring 109 urging the ball onto the seat element.

The seat element 1M has an opening 110 in its end face through which liquid fuel in the annular space 111 can pass, the annular space 111 in turn being fed with fuel through passageway 136 connected internally with inlet 14a on the body of the apparatus.

The strength of the spring 109 is selected to provide opening of the threshold valve at a predetermined low pressure which is greater than any gravitational pressure of fuel at the valve but less than fuel injection pressure, for example about 2 lbs. per square inch. This can be developed by the low pressure fuel pump'13. The valve is thus effective to prevent draining of fuel through the carubrettor device gravitationally when the engine and fuel injection apparatus is at rest.

The valve element 103 also includes a head 113 which is a close fit in the smaller diameter portion 102 of the carburettor bore and is equipped with a sealing ring 114- seated in a groove to seal the annular space 111 from the remaining portion of the carburettor bore.

The jet assembly includes a further jet element 115 in the form of an outer tube fitting telescopically with the inner tube 104 and formed with holes 116 constituting a jet orifice extending through its wall at diametrically opposed positions adjacent to the free or delivery end of the inner tube 104.

The carubrettor device further comprises two valves, namely a fuel cut-off valve and an air cut-off valve.

The valves comprise a plunger 117 incorporating or operable by a piston portion 117a and movable axially in the larger diameter section rm of the carburettor bore between an open position, as seen in FIG. 3, and a closed position in which its inner end overlaps the mouth or opening of an air passageway 1111b traversing the larger diameter portion 1111 of the carburettor bore situated in the vicinity of the free or delivery end of the inner tube 1114. Air is admitted to this passageway by pipe 1111a (FIG. 41) which may be connected to an air cleaner (not shown), the passageway continuing by way of a portion 1111b (1 1G. 4) connecting the carburettor bore and the chamber 34.

The fuel shut-off valve further comprises a valve eleemnt 118 of resilient material seated in the bottom of a bore 119 in the plunger 117, which bore constitutes a continuation of the interior surface of the outer tube 115 of the jet assembly.

The plunger 117 is biased by means of a coiled compression spring 1211 acting between the head 113 and the plunger 11'? to maintain the latter in a position in which both the fuel cut-off and air cut-off valves are Movement of the plunger 117 to closeboth of these valves takes place in responseto the admission of fuel under pressure from the outlet of the high pressure pump 18 to the space 121 through bores 123 and 122 and space 131 which communicates with the outlet side of the high pressure pump through bore 131a (FIG. 4). The bore 123 is formed in an inlet plug fitting 124 screwing into an internally threaded end portion of the carburettor bore, such fitting being equipped with a sealing ring 125 seated in a circumferential recess therein.

The bore 123 may contain a restrictor bush 126 formed with a constructor passageway 127 to control the rate of admission of fuel under pressure to the space 121 and hence to determine the duration of the starting period for which the carburettor device remains operative, such period terminating with closure of the fuel and air cut-off valves under injecting pres sure of fuel in the space 121.

When the throttle valve of the fuel injection device of the inner tube 104 and emerging from the holes 116 in the outer tube 1 15 will thus readily be broken up into particles in the manner of a slow running jet assembly of the conventional carburettor, and will be conveyed along the passageway 101b connecting the carburettor device e to the chamber 34 of air inlet duct of the fuel injection apparatus. p

The carburettordevice is also able to supply fuel to the engine in the event of a fault developing in the high pressure fuel pump such as to prevent the pressure at the outlet thereof reaching a value at which it will effect delivery of fuel from the outlets of the fuel pump to the injectors, and such that the plunger 117 remains in the position shown in FIG. 3. For operation under these conditions the throttle valve 36 would be opened only to a slight extent.

Pressure control and relief of fuel delivered from the outlet of the high pressure fuel pump is regulated by a blow-off valve 31. This comprises a valve head 128 (FIG. 3) of conical form cooperating with a valve seat in a body 129 against which it is spring loaded by a coiled compression spring 130. High pressure fuel is fed through a bore 131a to a chamber 131 from which it passes througha filter 133 to the interior bore 134 of the body 129 of the blow-off valve. The latter opens at a pressure determined by the spring to discharge excess fuel to the portion 135 of the blow-off valve bore and thence to a passageway 136. The pamgeway 136 communicates with the annular space 111 from which excess fuel is fed back to the fuel tank via an outlet fitting 112.

' I claim:

1. In fuel injection apparatus for an internal combustion engine comprising a body having an air inlet duct, an adjustable throttle valve means controlling the flow of air through said duct to the engine, fuel inlet means, and fuel outlet means for connection tolone or more injectors, pump means for establishing flow of fuel from said inlet means to said outlet means and for establishing injecting pressure for delivery of fuel from said injector or injectors, metering means for delivering a measured quantity of fuel to said outlet means in each cycle of operation of the engine, drive means for driving said metering means in timed relation with the engine, sensing means controlling operation of the metering means for sensing parameters selected to provide a proper air-to-fuel ratio for a range of engine loads and external conditions of operation, and carburettor means including a carburettor air inlet passageway of smaller cross-sectional area than that of said air inlet duct, and communicating with the latter at a position downstream of said throttle valve means, a fuel jet element communicating at its inlet end with said fuel inlet means and having a delivery end mounted in fuel delivery relation with said carburettor air inlet passageway to deliver fuel thereto in response to depression of pressure in said air inlet duct below atmospheric pressure during starting of the engine, the improvement comprising:

a. air cut-off valve means movable between open and closed positions for establishing and cutting off air flow through said carburettor air inlet passageway,

b. fuel cut-off valve means movable between open and closed positions to provide for delivery and cut-off of fuel from said delivery end of said fuel jet element,

c. fluid pressure actuated operating means for said air cut-off valve means and said fuel cut-off valve means and connected by fuel duct means with an outlet of said pump means to close said cut-off valve means in response to the attainment of fuel injection pressure.

2. The improvement according to claim 1 wherein the carburettor device comprises:

a. a carburettor bore in said body of said apparatus,

b. said fuel jet element is mounted in said bore,

c. said carburettor air inlet passageway communicates with said bore at a position adjacent to said delivery end of said fuel jet element,

d. said air cut-off valve means and said fuel cut-off valve means are contained in said bore,

said air cut-off valve means and said fuel cut-off valve means comprise a plunger movable longitudinally of 10 said carburettor bore and incorporating or operated by said piston element.

4. The improvement according to claim 1 wherein:

a. said pump means includes two pumps, one of which is a high pressure pump and the other of which is a low pressure pump,

b. said low pressure pump is connected to said inlet means of the apparatus for supplying fuel thereto,

c. said fuel jet element has its inlet end operatively connected with said low pressure pump.

5. The improvement according to claim 1 wherein:

a. a threshold valve means is provided for controlling the supply of fuel to said carburettor means.

b. said threshold valve means includes biasing means for closing said valve,

0. said threshold valve means includes a valve element movable against said biasing means from a closed position in response to attainment of a threshold pressure of fuel greater than the gravitational pressure of fuel established at said fuel jet element when the apparatus is idle but less than said injection pressure. 

1. In fuel injection apparatus for an internal combustion engine comprising a body having an air inlet duct, an adjustable throttle valve means controlling the flow of air through said duct to the engine, fuel inlet means, and fuel outlet means for connection to one or more injectors, pump means for establishing flow of fuel from said inlet means to said outlet means and for establishing injecting pressure for delivery of fuel from said injector or injectors, metering means for delivering a measured quantity of fuel to said outlet means in each cycle of operation of the engine, drive means for driving said metering means in timed relation with the engine, sensing means controlling operation of the metering means for sensing parameters selected to provide a proper air-to-fuel ratio for a range of engine loads and external conditions of operation, and carburettor means including a carburettor air inlet passageway of smaller crosssectional area than that of said air inlet duct, and communicating with the latter at a position downstream of said throttle valve means, a fuel jet element communicating at its inlet end with said fuel inlet means and having a delivery end mounted in fuel delivery relation with said carburettor air inlet passageway to deliver fuel thereto in response to depression of pressure in said air inlet duct below atmospheric pressure during starting of the engine, the improvement comprising: a. air cut-off valve means movable between open and closed positions for establishing and cutting off air flow through said carburettor air inlet passageway, b. fuel cut-off valve means movable between open and closed positions to provide for delivery and cut-off of fuel from said delivery end of said fuel jet element, c. fluid pressure actuated operating means for said air cut-off valve means and said fuel cut-off valve means and connected by fuel duct means with an outlet of said pump means to close said cut-off valve means in response to the attainment of fuel injection pressure.
 2. The improvement according to claim 1 wherein the carburettor device comprises: a. a carburettor bore in said body of said apparatus, b. said fuel jet element is mounted in said bore, c. said carburettor air inlet passageway communicates with said bore at a position adjacent to said delivery end of said fuel jet element, d. said air cut-off valve means and said fuel cut-off valve means are contained in said bore, e. said operating means comprises a piston element in said bore, f. said fuel duct means communicates with said bore at one side of said piston element to move same in a direction to close said air cut-off valve means and said fuel cut-off valve means.
 3. The improvement according to claim 2 wherein said air cut-off valve means and said fuel cut-off valve means comprise a plunger movable longitudinally of said carburettor bore and incorporating or operated by said piston element.
 4. The improvement according to claim 1 wherein: a. said pump means includes two pumps, one of which is a high pressure pump and the other of which is a low pressure pump, b. said low pressure pump is connected to said inlet means of the apparatus for supplying fuel thereto, c. said fuel jet element has its inlet end operatively connected with said low pressure pump.
 5. The improvement according to claim 1 wherein: a. a threshold valve means is provided for controlling the supply of fuel to said carburettor means. b. said threshold valve means includes biasing means for closing said valve, c. said threshold valve means includes a valve element movable against said biasing means from a closed position in response to attainment of a threshold pressure of fuel greater than the gravitational pressure of fuel established at said fuel jet element when the apparatus is idle but less than said injection pressure. 